Chi Aquarii is a star in the equatorial constellation of Aquarius. Its name is a Bayer designation that is Latinized from χ Aquarii, and abbreviated Chi Aqr or χ Aqr. The distance to this star, based upon parallax measurements with a 7% margin of error,[1] is 530 light-years (160 parsecs). It is visible to the naked eye with an apparent visual magnitude of about 5.[2]

The variability of the brightness of Chi Aquarii was announced by Joel Stebbins and Charles Morse Huffer in 1928, based on observations made at Washburn Observatory.[3] It is classified as a semi-regular variable star and its brightness varies by an amplitude of 0.0636 in magnitude.[4] The identified pulsation periods are 32.3, 38.5, and 44.9 days.[5]

This is an aging red giant star with a spectral classification of M3 III.[6] After the supply of hydrogen at its core was exhausted, it evolved off the main sequence, expanding to about 142 times the radius of the Sun.[7] The star is radiating 2,598 times the luminosity of the Sun from its enlarged photosphere at an effective temperature of 3,456 K.[7]

References

  1. ^
  2. ^ Samus, N. N. & Durlevich, O. V. et al. (2009), "VizieR Online Data Catalog: General Catalogue of Variable Stars (Samus+ 2007-2013)", VizieR On-line Data Catalog: B/GCVS. Originally Published in: 2009yCat....102025S. 1, Bibcode:2009yCat....102025S
  3. ^ Stebbins, Joel & Huffer, C. M. (1928), "The Constancy of the Light of Red Stars", Publications of the Washburn Observatory. 15: 137–174, Bibcode:1928PWasO..15..137S, retrieved 5 December 2024
  4. ^ Koen, Chris & Eyer, Laurent (March 2002), "New periodic variables from the Hipparcos epoch photometry", Monthly Notices of the Royal Astronomical Society. 331 (1): 45–59, arXiv:astro-ph/0112194. Bibcode:2002MNRAS.331...45K. doi:10.1046/j.1365-8711.2002.05150.x. S2CID 10505995
  5. ^ Tabur, V. et al. (December 2009), "Long-term photometry and periods for 261 nearby pulsating M giants", Monthly Notices of the Royal Astronomical Society. 400 (4): 1945–1961, arXiv:0908.3228. Bibcode:2009MNRAS.400.1945T. doi:10.1111/j.1365-2966.2009.15588.x. S2CID 15358380
  6. ^ Crampton, D. & Lloyd Evans, T. (1973), "Spectroscopic observations of M giant stars at the South Galactic Pole", Monthly Notices of the Royal Astronomical Society. 162: 11–15, Bibcode:1973MNRAS.162...11C. doi:10.1093/mnras/162.1.11
  7. ^ McDonald, I. et al. (15 June 2017), "Fundamental parameters and infrared excesses of Tycho–Gaia stars", Monthly Notices of the Royal Astronomical Society. 471 (1): 770–791, arXiv:1706.02208. Bibcode:2017MNRAS.471..770M. doi:10.1093/mnras/stx1433. ISSN 0035-8711